The Smiling Lens

This isSDSS J103843.08+484916.1. It’s a gravitational lens in Ursa Major that Jean calls the ‘Smilie’; and you can see why!

So what is the cause of the arcs around the central galaxies?

Gravitational lensing is due to the curvature of space. Think of a bowling ball on a trampoline, the trampoline is the fabric of space and the bowling ball is the mass – say a cluster of galaxies – bending it. The more mass the bowling ball has the more it will bend the trampoline, and the same goes for objects in space.

The arcs are in fact distorted images of a galaxy that is lurking behind the central galaxies you can see in the image; you can see it much clearer in this Hubble images here. The light from the galaxy behind has followed the curvature of space caused by the huge mass of the central objects, making the light bend around the galaxies as arcs.

The left golden fuzzy has a redshift, Z, 0f 0.426, making it around 4.5 billion light years distant. The galaxy that forms the arcs however could be much further away.